Cationic water-soluble polyamide-epichlorohydrin resins and method of preparing same



CATIONIC WATER-SOLUBLE POLYAM'IDE-EPI- CI-ILOROHYDRIN RESINS AND METHOD OF PREPARING SAME Gerald I. Keim, West Grove, Pa., assignor to Hercules Incorporated, Wilmington, Del., a corporation of Delaware Y No Drawing. Continuation of application Ser. No. 510,943, Dec. 1, 1965, which is a continuation of application Ser. No. 282,579, May 23, 1963. This application June 16, 1966, Ser. No. 557,914 a 10 Claims. (Cl. 260--29.2)

This application isa continuation of application Ser.

.No. 510,943, filed Dec. 1, 1965, now abandoned, which application is a continuation of application Ser. No.

282,579, filed May 23, 1963, now abandoned, which application is a continuation-in-part of application Ser.

-No. 850,762,.filed Nov. 4, 1959, now abandoned, which is a continuation-in-part of application Ser. No. 682,089, filed Sept. 5, 1957, now abandoned.

This invention relates to cationic thermosetting polyamide-epichlorohydrin resins and to a method of preparing same.

Very eflicient, alkaline-curing, wet-strength resins for paper may be prepared by reacting epichlorohydrin with basic polyamides whose basicity is essentially due to the presence of secondary amino groups. However, due to the relatively slow rate of cure of these resins, paper containing same develops wet strength slowly on the paper machine andalso during storage. Mo'reover, these resins are stabilized by adjusting the pH below 7.0.

It has now been discovered that fast-curing, efiicient resins may be prepared by reacting epichlorohydrin with .a basic polyamide whose basicity is essentially due to the Two hundred ninety grams (2.0 moles) of methyl bis (3-aminopropyl)amine and 100 ml. of water were weighed into a round-bottom, 3-necked flask equipped with'a thermometer, mechanical stirrer and a take-01f condenser. The agitator was started and 290 grams (2.0

United States Patent 'moles) of adipic acid was added in 6 equal parts over a" period of 10 minutes. The charge was heated to 165. .C- and held there for 24 hours, cooled to 75 C. an d 400 -rnl. of water was added. The product was then cooled to 25 C. and bottled. The product had a solids content of 64.9% and an intrinsic viscosity (measured in a 1.0 normal NH Cl solution) of 0.140.

Ninety-seven grams of his polyamide solution was dissolved in 450.0 grams of'water and transferred to a 3-necked; round-bottom fiask equipped with thermometer, mechanical agitator and dropping funnel. The agitator was started and the charge was heated to 50 C. Twenty-four grams of epichlorohydrin (1.05 moles of epichlorohydrin per mole of tertiary amine in the polyamide) was added dropwise over a period of 10 minutes. The temperature was raised to C. and maintained between 60 and 70 C, until the viscosity of the resin reached E (Gardner scale at 25 C.). The reaction was then terminated by adding 300 ml. of water and 10 ml.

3,332,901 Patented July 25, 1967 Example 2 i Three hundred grams (2.07 moles) of methyl bis(3- aminopropyl)amine and grams of water were weighed into a glass autoclave equipped with thermometer, me- Chanical stirrer and distillation condenser. The agitator was started and 290 grams (2.0 moles) of adipic acid was added in 6 equal portions over a period of 10 minutes. During this addition, the pot temperature was from 50 C. to 98 C. Heat was applied to the autoclave and the temperature raised to 170 C. It was held between 170177 C. fOr 4 hours. The charge was cooled to C. and 400 grams of water was added after which it was cooled to 25 C. The product contained 57.8% solids. It had an intrinsic viscosity of 0.132, an acid number of 10.3 and a tertiary amine content, calculated as triethylamine, of 2.9%.

Two hundred eighteen grams of this polyamide solution and 460.0 grams of water were weighed into a 3- necked, round-bottom flask equipped with mechanical stirrer, thermometer and dropping funnel. The charge was heated to 50 C. and 62.0 grams of epichlorohydrin (1.37 moles of epichlorohydrin per mole of tertiary amine in the polyamide) was added dropwise over a period of 3 minutes. The flask was then heated at 60-64 C. and held there until the viscosity of a 25% solids solution of theresin reached D (Gardner scale of 25 C.). The resin was then cooled rapidly to 25 C. and the pH adjusted from 9.0 to 8.0 with 1 drop of concentrated sul- .a viscosity of 65 cps. (Brookfield).

Example 3 Forty-eight and one-half grams of the polyamide utilized in Example 1 and 225.0 grams of water were weighed into a 3-necked, round-bottom flask equipped with stirrer, thermometer and dropping funnel. The charge was heated to 50 C. and 14.0 grams of epichlorohydrin (1.22 moles of epichlorohydrin per mole of tertiary amincin the polyamide) was addeddropwise over a period of 3 minutes. The iiask was then heated to 70 C. and maintained between 6070 C. until the Viscosity of. the resin reached 0 (Gardner scale at 25 C.). In order to stop the reaction, of water was added and the resin was cooled to 25 C. The product contained 7.7% solids and had a pH of 8.0 and a viscosity of 96.5 cps. (Brookfield).

Example 4 and had an intrinsic viscosity at 25 C. of about 0.120.

To 100 parts of this polyamide solution was added about 395 parts of water. This solution was heated to 50C. and 25.5 parts of epichlorohydrinwas added. The mixture was then heated to about 70 C. until it had obtaineda viscosity of DE (Gardner scale at 25 C. and

14.5% solids). Then 181.8 parts of water was added to the product, it was cooled to 25 C.30 C. and suflicient 10% HCl added to adjust the pH to about 5.0 The prod- 3 hot contained about 10% solids and had a Gardner viscosity at 25 C. of C-D.

The polyamide-epichlorohydrin resins of Examples 1, 2 and 3 were each evaluated in paper in comparison with flask was heated to 50 C. By means of the dropping funnel, 9.5 g. of epichlorohydrin was added dropwise in two minutes. Then, the temperature of the reactants was raised to 65 C. and maintained between 60-70 C. until the polyamide-epichlorohydrin resin, prepared as above 5 the viscosity of the product reached D (Gardner scale described, as a control. Tacoma bleached kraft pulp was at 25 C.). The product was diluted with 150 ml. of water beaten in a Noble and Wood cycle beater to a Schoppe'rand cooled to 25 C. It had a pH of 8.2, a viscosity of Riegler freeness of 750 cc. The resins were added to the B (Gardner), and contained 8.2% solids. dilute stock in the proportioner of a Noble and Wood Example 7 handsheet machine. The stock was formed into hand- 10 sheets with a basis weight of 40 lb./ream and dried on Twenty-One e S1X4enths!- grams mole) of a laboratory drum drier t a moisture content of methyl p py and m Of Water Part of each set of handsheets was given an additional were Weighed into a small glass autoclave q pp Wlth (mm f 1 hour a 05 C. e w tensile strength of h thermometer, mechanical stirrer and a condenser. The pa er was measured after soaking in distilled water for agitator Was Started and smole) of Subem 2 hours at 25 C. Results are given in Table I below. acid Was added- The autoelavve Was e w y heated to 170 C. and maintained at 170-l73 C. for four hours. TABLE I Approximately 12.5 'g. of distillate was collected during the reaction. The charge was cooled to 140 C. and dis- Percent solved in 40 g. of water. The product was an aqueous Resin Sample l a ge% lbT/ir if fii iig Solution of a basic polyamide containing 53.2% solids.

DTYPUIP lbJin- Thirty-three grams of the above polyamide and 95.4 welght g. of water were weighed into a 250-ml., round-bottom, Exam 1e 1 v p 7 0 4 5 6 7 0 three-necked flask equipped with mechanical agitator and p f 1 1 thermometer. The agitator was started, the charge was Control 9-3 g-g g-g heated to 50 C. and 5.7 g. of epichlorohydrin (1 mole From Ex'gmpl g 1 1 11 epichlorohydrin per mole of tertiary amine groupsin Comm-L 3-2 3-? polyamide) was added. The temperature of the solution 1 1 113 was then raised to 65 C. and held between 65-70 C. From Exemp1e3 until the viscosity of the resin reached H on the Gardner 1.0 7.6 9.8 a nt- 1 M 4,5 8,4 scale (measured at 25 C.). The polymerization was terminated by adding 325 g. of water. The final product was a clear, almost colorless solution with a pH of 8.6, Example 5 a viscosity of A and containing 4.6% solids. A resin similar to the polyamide-epichlorohydrin resin Example of Example 1 was divided into 3 parts and adjusted to The resins produced in Examples 6 and 7 above were pH 7.0, 5.0, and 2.0, respectively. The latter sample gelled evaluated in bleached kraft pul beaten to a s ho perin 5 days. The pH of the first two samples was checked Riegler freeness of 750 cc. The resins were added to the after 5 days and found to be 8.65 and 8.50 respectively. pulp in the proportioner of a Noble and Wood hand- The sample initially adjusted to pH 5.0 gelled in 4 months sheet machine at a pH of 7.5. The stock 'was formed into While the Sample a j to P Was Still quite fluidhandsheets with a basis weight of 40 lb./ ream. The hand- It thus pp that reducing the P eubstahtialty sheets were dried on a drum drier to a moisture content W ey for a few y decreases the Shelf Me of of 4%. A portion of the handsh'ee'ts was given an addithese Yesms- V tional cure of one hour at 105 f C. The wet tensile tests Example 6 were done on l-inch strips of the paper which had been Two hudred and ninety grams (2 moles) of methyl bis soaked for two hours in distilled water. The results are (3-aminopropyl)amine was weighed into a three-necked, given in the Table H below.

TABLE II Percent I Resin Basis Dry Wet Wet Resin Sample Added Weight Tensile, Tensile, Tensile, Based ofHandlbs/in. I lbs/1n. J Cured, on Bone sheets, lb. lbs/in. 1 Dry Pulp From Example 6 0. 5 i 140 26 3. 6 '4. 6 1.0 40 26 4.7 6.2 From Example 7 0. 5 40 26 5. 5 7. 6 1.0 40 26. 6.9 9.4

round-bottom flask equipped with thermometer, mechancal stirrer, [and condenser. The agitator was started and 268 grams (2 moles) of diglycolic acid was added. The :harge was slowly heated to 160 C. After two hours at C., "66.5 ml. of water had been distilled off. The :harge was cooled to 140 C. and 400 ml. of water was added and the solution was cooled to room temperature. It contained 56.5% solids.

Forty-three grams of the above polyamide and 200 g. f water were weighed into a three-necked, round-bottom lask equipped with stirrer, thermometer and dropping funnel. The agitator was started and the contents of the primary amino groups and at least one tertiary amino group with a saturated aliphatic dicarboxylic acid such as adipic acid and suberic acid, or with diglycolic acid. Blends of two or more of these dicarboxylic acids may also be used, as well as blends of one or more of these with higher saturated aliphatic dicarboxylic acids as long as the resulting long-chain polyamide is water-soluble or at least water-dispersible.

The polyamine reactant should have at least three amino groups, at least one of which is a tertiary amino group. It may also have secondary amino groups in limited amounts. Typical polyamines of this type suitable for use as hereinabove described are methyl bis(3-aminopropyl) amine, methyl bis(2-aminoethyl)amine, N-(Z-aminoethyl) piperazine, 4,7-dimethyltriethylenetetramine and so The temperatures employed for carrying out the reaction between the dicarboxylic acid and the polyamine may vary from about 110 C. to about 250 C. or higher at atmospheric pressure. For most purposes, however, temperatures between about 160 C. and 210 C. have been found satisfactory and are preferred. Where reduced pressures are employed, somewhat lower temperatures may be utilized. The time of reaction depends on the temperatures and pressures used and will ordinarily vary from about 1 to about 4 hours, although shorter or longer reaction times may be utilized depending on reaction conditions. In any event, the reaction is desirably continued to substantial completion for best results.

In carrying out the reaction, it is preferred to use an amount of dicarboxylic acid sufficient to react substantially completely with the primary amine groups of the polyamine. This will usually require a mole ratio of polyamine to dicarboxylic acid of from'about 0.9:1 to about 1.221 and preferably from about 0.92:1 to 1.14:1. However, mole ratios of from about 0.8:1 to about 1.4:1 may be used with quite satisfactory results. Mole ratios outside of these ranges are generally unsatisfactory. Thus, mole ratios below about 0. 8:1 result in a gelled product or one having a pronounced tendency to gel while mole ratios above about 1.421 result in low molecular weight polyamides. Such products do not produce efficient wetstrength resins when reacted with epichlorohydrin.

'Basic polyamides suitable for use herein may also be prepared from the long-chain polyamides described in my copending application Ser. No. 796,743 filed Mar. 3, 1959, now US. Patent No. 2,926,154 dated 'Feb. 2 3, 1960, by alkylating secondary amine groups of such long-chain polyamides to tertiary amine groups using alkyl halides, such as methylchloride and ethyl bromide, dimethyl sulfate, diazomethane, benzyl chloride or other suitable alkylating agent.

In converting the polyamide formed as above described to a cationic thermosetting resin, it is reacted with epichlorohydrin at a suitable temperature, i.e., at a temperature from about 25 C. to about 70 C., until the viscosity of the 20% solid solution at 25 C. has reached about C. or higher on the Gardener-Holdt scale. This reaction is preferably carried out in aqueous solution to moderate the reaction. The reaction may also be moderated by decreasing the pH of the aqueous polyamide solution with acid prior to addition of epichlorohydrin or immediately after the addition of epichlorohydrin. This adjustment is usually made to pH 8.5-9.5 but may be made to pH 7.5 in some cases with quite satisfactory results.

When the desired viscosity is reached, sufficient water is then added to adjust the solids content of the resin solution to about 25% or less, the product cooled to about 25 C. and then stabilized by adjusting the pH to about 7.0 to 9.0 and preferably to about 7.0 to 8.0. In some cases, pH adjustment will not be necessary at all since the final pH of the product will fall within the desired range.

In the polyamide-epichlorohydrin reaction, it is preferred to use sufficient epichlorohydrin to react with substantially all of the tertiary amine groups. However, more or less may be added to moderate or increase reaction rates. In general, it is contemplated utilizing from about 0.8 mole to about 2.0 moles of epichlorohydrin per mole of polyamide amine. It is preferred to utilize from about 1.0 mole to about 1.7 moles of epichlorohydrin per mole of polyamide amine.

The polyamide-epichlorohydrin resins, prepared as herein described, may be incorporated into pulp slurry at any point on the wet end of the paper machine. They may also be applied from a tub size or at a size press or form showers to the dry or partially dried sheet. For most purposes, adequate wet strength may be obtained by incorporating in the paper from about 0.25% to about 3% of the resin based on the dry weight of the pulp. However, in special cases up to 5% or more may be used.

It will thus be seen that the present invention provides polyamide-epichlorohydrin resins which are faster curing than previous resins of this type and which may be stabilized at pHs-near neutrality thus reducing corrosion problems. While these resins have been described and exemplified in connection with their use as wet-strength resins for paper, they may also be used for various other purposes such as for insol-ubilizing water-soluble ums, as retention aids for such products as wax emulsions, ketene dimer emulsions and mineral fillers, as flocculating agents for pulp fines, clays and the like, and as an anchor coat to unite regenerated cellulose with a film such as nitrocellulose for reducing moisture vapor transmission of the cellulose film. While preferred embodiments of the invention have been described, the invention is not to be construed as limited thereby except as the same may be included in the following claims.

What I claim and desire to protect by Letters Patent is:

1. A process of preparing an aqueous solution of a cationic, water-soluble thermosetting resin which comprises (1) reacting by heating together at temperatures from about 40 C. to about 70 C. epichlorohydrin and an aliphatic long-chain basic water-soluble polyamide selected from the group consisting of (a) polyamides formed by reacting a polyalkylene polyamine having two primary amino groups and from one to three tertiary amino groups, with a dicarboxylic acid selected from the group consisting of adipic acid, suberic acid, and diglycolic acid in a mole ratio of polyalkylene polyamine to dicarboxylic acid of from about 0.821 to about 1.4:1 and (b) polyamides formed by reacting a polyalkylene polyamine having two primary amino groups and at least one secondary amino group with a dicarboxylic acid selected from the group consisting of adipic acid, suberic acid, and diglycolic acid, the mole ratio of polyalkylene polyamine to dicarboxylic acid being from about 0.8:1 to about 1.411 and reacting the polyamide with an alkylating agent to convert at least 70% of the secondary amino groups to tertiary amino groups, the basicity of said polyamide being due essentially to the presence of tertiary amino groups, said tertiary amino groups constituting at least 70% of the basic nitrogen groups present in the polyamide, and the mole ratio of epichlorohydrin to amino groups of said polyamide being from about 0.8:1 to about 20:1, (2) continuing the reaction until an aqueous solution of a water-soluble cationic thermosetting resin is formed, and

then (3) terminating the reaction.'

2. A process of preparing an aqueous solution of a cationic, water-soluble thermosetting resin which comprises (1) reacting by heating together at temperatures from about 40 C. to about 70 C. epichlorohydrin and an aliphatic long-chain basic water-soluble polyamide for-med by reacting a polyalkylene polyamine having two primary amino groups and from one to three tertiary amino groups with a dicarboxylic acid selected from the group consisting of adipic acid, suberic acid, and diglycolic acid in a mole ratio of polyalkylene polyamine to dicarboxylic acid of from about 0.821 to about 1.4:1, the basicity of said .polyamide being due essentially to the presence of tertiary "amino groups, said tertiary amino groups constituting at least 70% of the basic nitrogen groups present in the polyarnide, and the mole ratio of epichlorohydrin to amino groups of said polyamide being from about 0.8:1 to about 2.0: 1, (2) continuing the reaction until an aqueous solution of a water-soluble cationic thermosetting resin is formed, and then (3) terminating the reaction.

3. A process of preparing an aqueous solution of a cationic, water-soluble thermosetting resin which comprises (1) reacting by heating together at temperatures from about 40 C. to about 70 C. epichlorohydrin and an aliphatic long-chain basic Water soluble polyamide formed by reacting a polyalkylene polyamine having two primary amino groups and at least one secondary amino group with a dicarboxylic acid selected from the group consisting of adipic acid, suberic acid, and diglycolic acid, the mole ratio of polyalkylene polyamine to dicarboxylic acid being from about 0.8:1 to about 1.4:1, and reacting the polyamide with an alkylating agent to convert at least 70% of the secondary amino groups of said polyamide to tertiary amino groups, the basicity of said polyamide being due essentially to the presence of tertiary amino groups, said tertiary amino groups constituting at least 70% of the basic nitrogen groups present in the polyamide, and the mole ratio of epichlorohydrin to amino groups of said polyarnide being from about 0.821 to about 2.021, (2) continuing the reaction until an aqueous solution of a water-soluble cationic thermosetting resin is formed, and then (3) terminating the reaction.

4. A process according to claim 2 in which the polyalkylene polyamine is met-hyl bis(3-aminopropyl)amine.

5. A process according to claim 4 in which the dicarboxylic acid is adipic acid.

6. A cationic water-soluble thermosetting resin produced by the proces of claim 1.

7. A cationic water-soluble thermosetting resin produced by the process of claim 2.

8. A cationic water-soluble thermosetting resin produced by the process of claim 3.

9. A cationic water-soluble thermosetting resin produced by the process of claim 4.

10. A cationic water-s0luble thermosetting resin produced by the process of claim 5.

References Cited UNITED STATES PATENTS 2,882,185 4/1959 Valko et a1 260-78 3,197,427 7/1965 Schmalz 26029.2 3,215,654 11/1965 Schmalz 260--29.2

FOREIGN PATENTS 446,643 8/3/1942 Belgium.

MURRAY TILLMAN, Primary Examiner.

J. C. BLEUTGE, Assistant Examiner. 

1. A PROCESS OF PREPARING AN AQUEOUS SOLUTION OF A CATIONIC, WATER-SOLUBLE THERMOSETTING RESIN WHICH COMPRISES (1) REACTING BY HEATING TOGETHER AT TEMPERATURES FROM ABOUT 40*C. TO ABOUT 70*C. EPICHLOROHYDRIN AND AN ALIPHATIC LONG-CHAIN BASIC WATER-SOLUBLE POLYAMIDE SELECTED FROM THE GROUP CONSISTING OF (A) POLYAMIDES FORMED BY REACTING A POLYALKYLENE POLYAMINE HAVING TWO PRIMARY AMINO GROUPS AND FROM ONE TO THREE TERTIARY AMINO GROUPS, WITH A DICARBOXYLIC ACID SELECTED FROM THE GROUP CONSISTING OF ADIPIC ACID, SUBERIC ACID, AND DIGLYCOLIC ACID IN A MOLE RATIO OF POLYALKYLENE POLYAMINE TO DICARBOXYLIC ACID OF FROM ABOUT 0.8:1 TO ABOUT 1.4:1 AND (B) POLYAMIDES FORMED BY REACTING A POLYALKYLENE POLYAMINE HAVING TWO PRIMARY AMINO GROUPS AND AT LEAST ONE SECONDARY AMINO GROUP WITH A DICARBOXYLIC ACID SELECTED FROM THE GROUP CONSISTING OF ADIPIC ACID, SUBERIC ACID, AND DIGLYCOLIC ACID, THE MOLE RATIO OF POLYALKYLENE POLYAMINE TO DICARBOXYLIC ACID BEING FROM ABOUT 0.8:1 TO ABOUT 1.4:1 AND REACTING THEH POLYAMIDE WITH AN ALKYLATING AGENT TO CONVERT AT LEAST 70% OF THE SECONDARY AMINO GROUPS TO TERTIARY AMINO GROUPS, THE BASICITY OF SAID POLYAMIDE BEING DUE ESSENTIALLY TO THE PRESENCE OF TERTIARY AMINO GROUPS, SAID TERTIARY AMINO GROUPS CONSTITUTING AT LEAST 70% OF THE BASIC NITROGEN GROUPS PRESENT IN THE POLYAMIDE, AND THE MOLE RATIO OF EPICHLOROHYDRIN TO AMINO GROUPS OF SAID POLYAMIDE BEING FROM ABOUT 0.8:1 TO ABOUT 2.0:1, (2) CONTINUING THE REACTION UNTIL AN AQUEOUS SOLUTION OF A WATER-SOLUBLE CATIONIC THERMOSETTING RESIN IS FORMED, AND THEN (3) TERMINATING THE REACTION. 